Coma is the severest impairment of arousal and is defined as the inability to obey commands, speak, or open the eyes to pain.
The Glasgow Coma Scale (GCS) is a widely used scoring system with good repeatability (note: the scale is used to assess level of consciousness and is not designed for following neurologic deficits). General practice is to record a “T” (for “intubated”) next to the verbal score and the total score for patients whose verbal axis cannot be assessed because of intubation.
No single GCS score defines a cutoff for coma, however, 90% of patients with GCS ≤ 8 and none with GCS ≥ 9 meet the above definition of coma. Thus, GCS ≤ 8 is a generally accepted operational definition of coma.
A number of scales for use in children have been proposed.